JP6315304B2 - Developing device, process cartridge, and image forming apparatus - Google Patents

Description

  The present invention relates to a developing device using a two-component developer including toner and a carrier, and a process cartridge and an image forming apparatus provided with the developing device.

  This type of developing device used in an image forming apparatus such as a printer, a facsimile machine, and a copying machine generally has two-component development along a developer supply / conveyance path extending in the direction of the rotation axis of the developer carrier along the developer carrier. The agent (hereinafter simply referred to as “developer”) is conveyed while stirring. Further, the casing that houses the developer and forms the developer supply / conveyance path has a developer carrying surface in the moving direction of the developer carrying body so that the surface of the developer carrying body faces the surface of the latent image carrying body. A developing opening for exposing a part of the body surface is provided. Further, the developer transported in the developer supply transport path disposed below the developer carrier is supported on the surface of the rotating developer carrier, and the developer is supported by the rotation of the developer carrier. Then, the developer carrying member exposed at the developing opening and the latent image carrying member are supplied to the developing regions facing each other. Further, some conventional developing apparatuses employ a supply / recovery integrated system in which the developed developer that has consumed toner in the development region is separated from the developer carrying member and returned to the developer supply / conveyance path (Patent Document 1). Thru 3 etc.).

  In this type of developing device, the surface of the developer carrier to which the developer is supplied from the developer supply conveyance path at the pumping position in the casing is moved from the developing opening to the outside of the casing by the surface movement of the developer carrier. It is exposed and reaches the development area. The surface of the developer carrying member that has passed through the development area moves to the inside of the casing by the surface movement, and the developed developer that has consumed toner in the development area is separated at a separation position in the casing. Then, the developer reaches the pumping position again, and the developer is supplied from the developer supply conveyance path. When the exposed surface of the developer carrying member moves into the casing, an air flow is generated that draws gas outside the casing into the casing.

When such an air flow is generated, the pressure inside the casing rises, and due to the pressure difference from the outside of the casing, the gas inside the casing flows out of the casing through the gap between the casings, and the toner in the developer together with this gas flows outside the casing. May leak out and cause toner leakage.
Patent Document 1 describes a configuration in which a through hole provided with a filter member that allows gas to pass while preventing the toner and magnetic carrier from passing is provided in the casing. By providing such a through hole, the pressure increase in the casing can be suppressed, and the occurrence of toner leakage can be suppressed. Further, in the developing device described in Patent Document 1, the opening on the casing inner side of the through hole is provided at a position facing the surface of the developer carrier upstream of the developer carrier in the surface movement direction from the separation position. Yes.

However, on the upstream side of the separation position, the developer carried on the developer carrying body moves together with the surface of the developer carrying body, and the airflow is also on the surface of the developer carrying body together with the surface of the developer carrying body and the developer. Move to the downstream side in the moving direction. For this reason, it is difficult to generate an air flow that goes to the opening of the through-hole arranged to face the upstream side of the separation position, and there is a possibility that the effect of suppressing the pressure increase in the casing cannot be sufficiently obtained. .
The developer separated from the developer carrier falls into the developer supply conveyance path, but at this time, the developer in the developer supply conveyance path merges with other developer, and the toner in the developer easily scatters. It becomes. Also, as the developer falls from the separated position into the developer supply transport path, the air flow brought along with the developer flows into the developer supply transport path, so that the air pressure increases in the developer supply transport path. Tend to.

  The scattered toner flows in a direction where the atmospheric pressure is low together with the airflow. In order to discharge the air flow in the developer supply / conveyance path from the through hole to the outside with the developing device of Patent Document 1, the developer is transported to the surface of the developer carrier to the separation position together with the developer, and the developer supply / conveyance from the separation position is performed. It is necessary to generate an airflow that flows backward with respect to the airflow flowing into the road. However, in order to generate such an air flow, it is necessary to generate a sufficient pressure difference between the position where the opening of the through hole is provided and the developer supply conveyance path. In a state where such a pressure difference occurs, if there is a portion with poor sealing performance in the vicinity of the developer supply conveyance path, an air flow is generated from the outside, and the scattered toner is removed from the casing of the developing device together with the air flow. Will be leaked.

  The present invention has been made in view of the above problems, and the object thereof is as follows. That is, there is provided a developing device that can more effectively suppress the toner in the two-component developer from flowing out of the casing, and a process cartridge and an image forming apparatus provided with the developing device by an integrated supply and recovery method. Is to provide.

In order to achieve the above object, the invention of claim 1 includes a developer carrying member that rotates so as to move from the lower side to the upper side in the developing region, and the surface of the developer carrying member is a surface of the latent image carrying member. A casing having a developing opening for exposing a part of the surface of the developer carrying member in the direction of movement of the developer carrying member so as to oppose, and housing a two-component developer containing toner and a magnetic carrier inside; The developer component is disposed in a developer supply transport path extending in the direction of the rotation axis of the developer support below the developer support in the casing, and the two-component developer in the developer supply transport path is used as the developer. A developer supply / conveying member that supplies the two-component developer in the developer supply / conveyance path to the surface of the developer support while transporting along the axial direction of the support; Two-component development supported on the surface To the developing area, in which the toner in the two-component developer is adhered to the latent image on the surface of the latent image carrier to develop the latent image, and the two-component developer that has passed through the developing area In a developing device that is separated from the developer carrier and collects in the developer supply conveyance path, a supply position at which a two-component developer is supplied from the developer supply conveyance path on the surface of the developer carrier. The upper end of the two-component developer that has passed through the development region is opposed to the surface between the developer carrier and the spaced position where the two-component developer is separated from the developer carrier. A partition plate located between a space where the supply position in the developing device faces and a space where the separation position opposes, and a lower end portion of the partition plate is located above the developer supply transport member; Passing toner and magnetic carrier The opening inside the casing of the through hole provided with a filter member that allows gas to pass while stopping is located in the vicinity of the lower end of the partition plate, and viewed from the direction of the rotation axis, the opening of the through hole inside the casing the opening width of the side is, in the space where the separation position is opposed, the two-component developer between the member opposed to the partition plate and the partition plate is characterized in that wider than the gap to be moved.

  According to the present invention, there is an excellent effect that the toner in the two-component developer can be more effectively suppressed from flowing out of the casing by the supply and recovery integrated system.

FIG. 3 is a cross-sectional explanatory view of the developing device according to the present embodiment. 1 is a schematic configuration diagram of a copier according to an embodiment. The schematic block diagram of an image creation unit. FIG. FIG. 3 is a top view schematically showing a developer circulation path in the developing device. FIG. 3 is an explanatory diagram showing the flow of airflow and developer in the developing device. The top view of the image development apparatus which abbreviate | omitted illustration of the image development upper case of a casing. FIG. 3 is an enlarged cross-sectional view in the vicinity of a partition plate of a developing device. Cross-sectional explanatory drawing of the developing device before the start of use. FIG. 3 is a perspective explanatory view of a developing device before use. The disassembled perspective view of a communicating port sealing member.

Hereinafter, an embodiment of a tandem color copying machine (hereinafter referred to as a copying machine 500) as an image forming apparatus to which the present invention is applied will be described.
FIG. 2 is a schematic configuration diagram of the copying machine 500. The copying machine 500 includes a document reading unit 4 and a document conveying unit 3 above a printer unit 100 as a main body unit of the image forming apparatus, and a sheet feeding unit 7 below the printer unit 100. The document conveying unit 3 conveys the document to the document reading unit 4, and the document reading unit 4 reads image information of the conveyed document. The paper supply unit 7 is a recording medium storage unit that stores transfer paper P that is a recording medium. The paper supply unit 7 stores a plurality of transfer papers P in a stacked manner, and the transfer paper P in the paper supply cassette 26. A paper feed roller 27 that feeds the printer unit 100. A one-dot chain line in FIG. 2 indicates a conveyance path of the transfer paper P in the copying machine 500.

  An upper portion of the printer unit 100 is a paper discharge tray 30 on which transfer paper P on which an output image is formed is stacked. The printer unit 100 includes four image forming units 6 (Y, M, C, K) as image forming units for forming toner images of respective colors (yellow, magenta, cyan, black), and an intermediate transfer unit 10. . Each image forming unit 6 (Y, M, C, K) includes a drum-shaped photoconductor 1 (Y, M, C, K) as an image carrier on which each color toner image is formed, and each photoconductor ( A developing device 5 (Y, M, C, K) for developing an electrostatic latent image formed on the surface of Y, M, C, K) is provided.

  The intermediate transfer unit 10 includes an intermediate transfer belt 8 stretched by a plurality of stretch rollers and a primary transfer bias roller 9 (Y, M, C, K). The intermediate transfer belt 8 is an intermediate transfer body on which the color toner images formed on the surface of each photoconductor 1 (Y, M, C, K) are transferred in a superimposed manner, and a color toner image is formed on the surface. . Further, the primary transfer bias roller 9 (Y, M, C, K) is applied with a transfer bias having a polarity opposite to the normal charging polarity of the toner, and on the surface of each photoreceptor 1 (Y, M, C, K). 1 is a primary transfer unit that transfers the toner image formed on the intermediate transfer belt 8 to the intermediate transfer belt 8. The image forming units 6 (Y, M, C, K) are arranged side by side so as to face the intermediate transfer belt 8 of the intermediate transfer unit 10.

  The printer unit 100 includes a secondary transfer bias roller 19 for transferring the color toner image on the intermediate transfer belt 8 onto the transfer paper P. Further, the printer unit 100 once stops the conveyance of the transfer paper P sent out by the paper feed roller 27 and adjusts the timing at which the intermediate transfer belt 8 and the secondary transfer bias roller 19 are conveyed to the opposing secondary transfer nip. A registration roller pair 28 is provided. Further, the printer unit 100 includes a fixing device 20 that fixes an unfixed toner image on the transfer paper P above the secondary transfer nip.

In addition, toner containers 11 (Y, M, C, and K) for each color are disposed below the paper discharge tray 30 in the printer unit 100 and above the intermediate transfer unit 10. Each color toner container 11 (Y, M, C, K) contains toner of each color (yellow, magenta, cyan, black) supplied to each developing device 5 (Y, M, C, K). Each color toner container 11 (Y, M, C, K) is detachably installed in the printer unit 100.
Further, below the four image forming units 6 (Y, M, C, K) in the printer unit 100, laser light L is irradiated on the surface of each photoconductor (Y, M, C, K). An exposure device 12 which is a latent image forming unit for forming an electrostatic latent image is provided.

FIG. 3 is an enlarged explanatory view of one of the four image forming units 6 (Y, M, C, K). The four image forming units 6 (Y, M, C, K) have substantially the same configuration and operation except for the color of the toner used in the image forming process. In the following description, symbols Y, M, C, and K indicating the above are omitted as appropriate.
FIG. 4 is a perspective explanatory view of the image forming unit 6. As shown in FIG. 4, the image forming unit 6 is a process cartridge that integrally supports the photosensitive member 1 and the developing device 5, and this process cartridge is detachable from the copying machine 500 main body. . This facilitates exchange of the developing device 5 in the main body of the copying machine 500 provided with the developing device 5, and improves the maintainability of the copying machine 500.

  The image forming unit 6 includes a photoconductor cleaning device 2 and a charging device 40 in addition to the developing device 5 around the photoconductor 1. In the image forming unit 6 of the present embodiment, the photoreceptor cleaning device 2 is configured to be cleaned by the cleaning blade 2a, and the charging device 40 is configured to be charged by the charging roller 4a. Further, the image forming unit 6 includes a charge eliminating unit (not shown) that removes the surface potential of the surface of the photoreceptor 1 after the transfer.

Hereinafter, an operation during normal color image formation in the copier 500 of the present embodiment will be described.
First, when a start button (not shown) is pressed in a state where the document is set on the document table of the document conveyance unit 3, the document is conveyed from the document table by the conveyance roller of the document conveyance unit 3, and the document reading unit 4. Placed on the contact glass. Then, the document reading unit 4 optically reads the image information of the document placed on the contact glass.

  Specifically, the document reading unit 4 scans an image of a document on the contact glass while irradiating light emitted from an illumination lamp. Then, the light reflected from the original is imaged on the color sensor via the mirror group and the lens. The color image information of the original is read for each color separation light of RGB (red, green, blue) by the color sensor, and then converted into an electrical image signal. Further, color conversion processing, color correction processing, spatial frequency correction processing, and the like are performed by the image processing unit based on the RGB color separation image signals to obtain yellow, magenta, cyan, and black color image information.

  Then, the image information of each color of yellow, magenta, cyan, and black is transmitted to the exposure device 12. The exposure device 12 emits laser light L based on the image information of each color toward the corresponding photoreceptor 1 (Y, M, C, K).

On the other hand, the four photoconductors 1 (Y, M, C, K) are rotated clockwise in FIGS. 2 and 3 by drive motors (not shown). First, the surface of the photoreceptor 1 (Y, M, C, K) is uniformly charged at a portion facing the charging roller 4a of the charging device 40 (charging process). As a result, a charged potential is formed on the surface of the photoreceptor 1 (Y, M, C, K). Thereafter, the surface of the charged photoreceptor 1 (Y, M, C, K) reaches a position where the laser beam L is irradiated.
In the exposure device 12, laser light L corresponding to the image signal is emitted from four light sources corresponding to each color. Each laser beam L passes through a different optical path for each color component of yellow, magenta, cyan, and black, and is irradiated on the surface of each photoreceptor 1 (Y, M, C, K) (exposure process).

  The laser beam L corresponding to the yellow component is applied to the surface of the first yellow photoreceptor 1Y from the left side of the drawing in FIG. At this time, the yellow component laser light L emitted based on the image signal from the exposure device 12 disposed below the yellow image forming unit 6Y is rotated at a high speed by a polygon mirror to rotate the rotation axis of the yellow photoconductor 1Y. Scanning is performed in the direction (main scanning direction). By irradiating the yellow photoconductor 1Y through the plurality of optical elements while being scanned with the laser light L in this manner, the surface of the yellow photoconductor 1Y after being charged by the charging device 40 is An electrostatic latent image corresponding to the yellow component is formed.

  Similarly, the laser beam L corresponding to the magenta component is irradiated onto the surface of the second magenta photoreceptor 1M from the left in FIG. 2, and an electrostatic latent image corresponding to the magenta component is formed. The cyan component laser light L is applied to the surface of the third cyan photoconductor 1C from the left in FIG. 2 to form an electrostatic latent image of the cyan component. The black component laser beam L is applied to the surface of the fourth black photoconductor 1K from the left in FIG. 2 to form a black component electrostatic latent image.

  Thereafter, the surface of the photoreceptor 1 (Y, M, C, K) on which the electrostatic latent images of the respective colors are formed reaches a position facing the developing device 5. Then, each color toner is supplied onto the surface of the photoreceptor 1 (Y, M, C, K) from the developing device 5 (Y, M, C, K) containing developer of each color toner and carrier, The latent image on the photoreceptor 1 (Y, M, C, K) is developed (development process). Thereby, a toner image of a corresponding color is formed on the surface of each photoreceptor 1 (Y, M, C, K).

  The surface of the photoreceptor 1 (Y, M, C, K) after passing through the developing area which is a portion facing the developing device 5 reaches a portion facing the intermediate transfer belt 8. Here, primary transfer bias rollers 9 (Y, M, C, and K) are installed at the opposing portions so as to contact the inner peripheral surface of the intermediate transfer belt 8. The photoconductor 1 (Y, M, C, K) and the primary transfer bias roller 9 (Y, M, C, K) face each other with the intermediate transfer belt 8 interposed therebetween, thereby forming a primary transfer nip. Then, the intermediate transfer belt 8 moves in the direction of the arrow in the figure (counterclockwise direction) and sequentially passes through the primary transfer nip of each primary transfer bias roller 9 (Y, M, C, K). At the primary transfer nip, the toner images of the respective colors formed on the respective photoreceptors 1 (Y, M, C, K) are sequentially transferred onto the intermediate transfer belt 8 (primary transfer process). As a result, a color toner image is formed on the intermediate transfer belt 8.

A small amount of untransferred toner remains on the surface of the photoreceptor 1 after passing through the primary transfer nip. The surface of the photoconductor 1 after passing through the primary transfer nip reaches a position facing the photoconductor cleaning device 2. The untransferred toner remaining on the photoconductor 1 is scraped off by the cleaning blade 2a at a position facing the photoconductor cleaning device 2 and mechanically collected (photoconductor cleaning process).
The surface of the photoconductor 1 that has passed through the portion facing the photoconductor cleaning device 2 passes through a charge removal unit that is opposed to a charge removal unit (not shown), and the residual charges are removed. Thus, a series of image forming processes on the photoconductor 1 is completed. In preparation for the next image forming operation.

  The color toner images on the four photoconductors 1 (Y, M, C, K) are transferred in an overlapping manner, and the intermediate transfer belt 8 carrying the color toner images moves on the surface counterclockwise in FIG. It reaches the secondary transfer nip which is a position facing the secondary transfer bias roller 19. In the secondary transfer nip, the intermediate transfer belt 8 is sandwiched between the secondary transfer bias roller 19 and one of the stretching rollers to form a secondary transfer nip.

On the other hand, when the paper feeding roller 27 of the paper feeding unit 7 is driven to rotate counterclockwise in FIG. 2, the uppermost transfer paper P among the transfer papers P stored in the paper feeding cassette 26 is fed. Sent. The transfer paper P fed by the paper feed roller 27 from the paper feed cassette 26 containing the transfer paper P is guided to the registration roller pair 28 after passing through the conveyance guide, hits the registration roller pair 28, and stops once. To do. The transfer paper P that has struck the registration roller pair 28 is rotated by the registration roller pair 28 in accordance with the timing at which the color toner image formed on the intermediate transfer belt 8 is directed to the secondary transfer nip. It is conveyed toward.
Then, the color toner image carried on the intermediate transfer belt 8 at the secondary transfer nip is transferred onto the transfer paper P (secondary transfer step).

  The surface of the intermediate transfer belt 8 that has passed through the secondary transfer nip reaches a portion facing an intermediate transfer belt cleaning device (not shown). At this facing portion, the transfer residual toner adhering to the intermediate transfer belt 8 is collected by an intermediate transfer belt cleaning device (not shown), and a series of transfer processes in the intermediate transfer belt 8 is completed.

Transfer residual toner that has not been transferred to the transfer paper P remains on the surface of the intermediate transfer belt 8 that has passed through the secondary transfer nip. The transfer paper P on which the color toner image is transferred at the secondary transfer nip is guided to the fixing device 20. In the fixing device 20, a color image is fixed on the transfer paper P by heat and pressure at a fixing nip formed by a fixing roller and a pressure roller (fixing step).
The transfer paper P that has passed through the fixing device 20 is discharged as an output image outside the printer unit 100 by the paper discharge roller pair 25 and stacked on the paper discharge tray 30 to complete a series of image forming processes.

FIG. 1 is a cross-sectional explanatory view of the developing device 5 of the present embodiment.
The developing device 5 includes a developing roller 50 including a magnet roller 55 as a magnetic field generating unit and a developing sleeve 51 as a developer carrier that rotates around the magnet roller 55. The developing roller 50 is provided in a developing roller accommodating portion 62 as a developer carrying member accommodating portion.
The developing sleeve 51 is a cylindrical member that includes a magnet roller 55 and is made of a rotatable nonmagnetic material. On the surface of the developing sleeve 51, as a plurality of magnetic poles, a first magnetic pole P1 (S pole), a second magnetic pole P2 (N pole), a third magnetic pole P3 (S pole), a fourth magnetic pole P4 (N pole), And the five magnetic poles of the fifth magnetic pole P5 (N pole) are formed by the magnet roller 55. Note that P1 to P5 in FIG. 1 indicate the distribution of the normal direction magnetic flux density (absolute value) on the surface of the developing sleeve 51 of the magnetic field formed by each magnetic pole.

  The developing sleeve 51 is subjected to blasting on the surface of the image forming region in the longitudinal direction (rotating axis direction) so that the developer can be favorably carried. A part of the surface of the developing sleeve 51 is partially exposed from the opening 61 of the casing 60 that forms the developing roller housing portion 62, and forms a developing region facing the photoreceptor 1.

  Further, a doctor blade 52 as a developer regulating member for regulating the layer thickness of the developer is provided on the upstream side in the surface movement direction of the developing sleeve 51 from the developing region. The doctor blade 52 faces the surface of the developing sleeve 51 below the rotation axis of the developing sleeve 51, and a magnetic plate 58 is provided adjacent to the upstream side of the surface of the developing blade 51 in the moving direction of the developing blade 51. Yes. The base of the magnetic plate 58 is supported on the upstream side surface of the doctor blade 52, and the tip side is bent substantially horizontally to form a facing surface 58 a that faces the surface of the developing sleeve 51 on the upstream side of the doctor blade 52. doing.

  Below the developing roller accommodating portion 62, a supply / recovery conveying path 53a and a circulating conveying path 54a are provided as a developer accommodating portion for accommodating a developer G, which is a two-component developer composed of a carrier and toner. As shown in FIG. 3, the circulation conveyance path 54 a communicates with the toner supply port 64 through an opening formed above the circulation conveyance path 54 a.

  The developer accommodating portion is partitioned by a partition wall 57 into a supply / recovery conveyance path 53 a on the developing sleeve 51 side and a circulation conveyance path 54 a on the toner supply port 64 side. The supply / recovery conveyance path 53a and the circulation conveyance path 54a on the toner supply port 64 side communicate with each other through an opening (not shown) provided at the end of the partition wall 57. The supply / recovery conveyance path 53 a on the developing sleeve 51 side includes a communication port 59 with the developing roller accommodating portion 62. A supply / recovery screw 53 and a circulation screw 54 for stirring and conveying the toner are provided in the supply / recovery conveyance path 53a and the circulation / conveyance path 54a, respectively. The supply / recovery screw 53 and the circulation screw 54 rotate counterclockwise as indicated by arrows in FIG.

The developer G in the developing device 5 is adjusted so that the ratio of toner in the developer (toner concentration) is within a predetermined range. Specifically, a toner replenishing device (not shown) is driven according to the consumption of toner in the developing device 5, and the toner stored in the toner container 11 (see FIG. 2) is circulated and conveyed through the toner replenishing device 54a. It is replenished inside.
A density detection sensor 56 for detecting the toner density of the developer is provided on the bottom surface of the circulation conveyance path 54a. When the density detection sensor 56 detects that the toner density is insufficient in the developer accommodating portion, a toner replenishing device (not shown) is driven, and enters the circulation conveyance path 54a from the toner container 11 (see FIG. 2) via the toner replenishing port 64. Toner is replenished.

  FIG. 5 is a top view schematically showing the circulation path of the developer G in the developing device 5, the broken arrow in FIG. 5 indicates the flow of the developer G, and the solid arrow in FIG. The flow of toner supplied from the toner supply port 64 is shown. In the developing device 5, the developer G in the supply / recovery conveyance path 53a is supplied to the development sleeve 51, and the developer G carried on the development sleeve 51 and passed through the development region is collected in the supply / recovery conveyance path 53a. . The density detection sensor 56 indicated by a broken-line square in FIG. 5 is installed below a portion of the casing 60 that forms the circulation conveyance path 54a.

Next, the operation of the developing device 5 will be described.
The toner replenished to the developing device 5 by the toner replenishing device is replenished from the toner replenishing port 64 into the circulation conveyance path 54a of the developer accommodating portion. The toner replenished to the circulation conveyance path 54 a of the developing device 5 is agitated with the developer G composed of toner and carrier by the circulation screw 54. In the circulation conveyance path 54 a, the developer G composed of toner and carrier and the replenished toner are conveyed in the axial direction while being agitated by the circulation screw 54, and the replenished toner is taken into the developer G.

  The developer G that has been transported to the circulation screw 54 and has reached the downstream end in the transport direction of the circulation transport path 54a passes through the opening at the end of the partition wall 57 (circulation downstream end opening 57a), and is supplied, recovered and transported. Move to the road 53a. The developer G in the supply / recovery conveyance path 53a is conveyed in the opposite direction to the developer G in the circulation / conveyance path 54a while being stirred by the supply / recovery screw 53. When the downstream end of the supply / recovery conveyance path 53a in the conveyance direction is reached, it passes through the opening at the end of the partition wall 57 (supply downstream end opening 57b) and moves to the circulation conveyance path 54a. As described above, the developer is circulated in the developer accommodating portion constituted by the supply / recovery conveyance path 53a and the circulation / conveyance path 54a by the supply / recovery screw 53 and the circulation screw 54. Further, as shown by arrows in FIGS. 1 and 3, the developing sleeve 51 rotates in the counterclockwise direction in the drawings.

  Of the developer G stirred and conveyed by the supply / recovery screw 53 in the supply / recovery conveyance path 53a, the developer G attracted to the developing sleeve 51 by the magnetic force of the fifth magnetic pole P5 of the magnet roller 55 is described later. And is carried on the developing sleeve 51. The developer G attracted by the magnetic pole of the fifth magnetic pole P5 is carried on the pumping portion 511 which is a supply position on the surface of the developing sleeve 51. The carrier in the developer G is attracted to the developing sleeve 51 by the magnetic force of the magnet roller 55 included in the developing sleeve 51 and is carried on the developing sleeve 51. In addition, the toner in developer G is charged with the opposite polarity to the carrier due to frictional charging with the carrier as developer G is agitated, and the electrostatic force acts between the carrier and is adsorbed to the carrier. The carrier is carried on the developing sleeve 51 together with the carrier. The developer G carried on the developing sleeve 51 moves around the developing roller 50 as the developing sleeve 51 rotates.

  The developer G carried on the developing sleeve 51 is conveyed counterclockwise in FIG. 1 as the developing sleeve 51 rotates, and reaches a position where the doctor blade 52 and the surface of the developing sleeve 51 face each other. Then, the developer G on the developing sleeve 51 passes through a gap (doctor gap) between the doctor blade 52 and the surface of the developing sleeve 51 at this position, so that the layer thickness is regulated, and the amount of the developer becomes an appropriate amount. Is done. On the upstream side of the doctor blade 52, a facing surface 58 a of the magnetic plate 58 is provided so as to face the developing sleeve 51. By the action of the facing surface 58a, the developer stirring function in the doctor blade 52 can be improved.

  When the developer G on the developing sleeve 51 that has passed through the doctor blade 52 is transported to the developing area facing the photosensitive member 1, the developer G stands on the developing sleeve 51 by the magnetic force of the magnet roller 55. Here, the developing sleeve 51 moves in the same direction in the developing region at a higher linear velocity than the surface of the photoreceptor 1. The carrier spiked on the developing sleeve 51 supplies the toner adhered to the carrier surface to the surface of the photoreceptor 1 while rubbing the surface of the photoreceptor 1. At this time, a developing bias is applied to the developing sleeve 51 from a power source (not shown), whereby a developing electric field is formed in the developing region.

Then, between the electrostatic latent image on the photosensitive member 1 and the developing sleeve 51, an electrostatic force directed toward the electrostatic latent image side acts on the toner on the developing sleeve 51. As a result, the toner on the developing sleeve 51 adheres to the electrostatic latent image on the photoreceptor 1. By this adhesion, the electrostatic latent image on the photoreceptor 1 is developed into a corresponding color toner image. Thereafter, the developer G that has consumed the toner on the developing sleeve 51 reaches the upper portion of the developing roller accommodating portion 62 as it rotates, and is separated from the developing sleeve 51 at this position.
At this time, the developer G on the surface of the developing sleeve 51 is developed by the action of magnetic force at the inflection point 512 formed by the fourth magnetic pole P4 and the fifth magnetic pole P5 which are adjacent magnetic poles of the same polarity (N pole). Detach from the surface of the sleeve 51.

Next, the characteristic part of the developing device 5 of the present embodiment will be described.
The developing device 5 includes a partition plate whose upper end faces the entire surface in the longitudinal direction of the developing sleeve 51 with respect to the surface between the pumping portion 511 on the developing sleeve 51 and the inflection point 512 serving as the agent separation magnetic pole. 520. The partition plate 520 divides the space where the pumping unit 511 is opposed to the space where the inflection point 512 is opposed in the developing device 5, and the lower end portion is located above the supply / recovery conveyance path 53 a.
Further, the casing 60 includes a pressure relief hole 92 provided with a pressure relief filter 90 that allows gas to pass while preventing the toner and the magnetic carrier from passing through. The opening of the pressure relief hole 92 inside the casing 60 is as follows. It is located near the lower end of the partition plate 520.

  The upper end of the partition plate 520 is opposed to the surface between the pumping portion 511 on the developing sleeve 51 and the inflection point 512, so that the developer G separated at the inflection point 512 is caused to incline the inclined surface 521 of the partition plate 520. It can be flowed up. The developer G separated at the inflection point 512 is collected in the supply / recovery conveyance path 53a through the space on the side facing the inflection point 512 across the partition plate 520 along the inclined surface 521 of the partition plate 520. On the other hand, the developer G supplied from the supply / recovery conveyance path 53a to the surface of the developing sleeve 51 is supplied to the surface of the developing sleeve 51 through a space on the side facing the pumping portion 511 with the partition plate 520 interposed therebetween. .

The path of the developer G separated by the inflection point 512 and the path of the developer G supplied to the pumping unit 511 can be partitioned by the partition plate 520. For this reason, it is possible to effectively prevent the developer G separated at the inflection point 512 from being mixed with the developer G supplied to the pumping unit 511. Therefore, it is possible to effectively supply the developer G separated at the inflection point 512 to the developing sleeve 51 immediately by the supply / recovery integrated system in which the developer G separated at the inflection point 512 is collected in the supply / recovery conveyance path 53a. Can be suppressed.
Further, in the developing device 5, the developer G separated from the developing sleeve 51 at the inflection point 512 can flow on the inclined surface 521 of the partition plate 520. Further, the presence of the partition plate 520 can prevent the separated developer G from being attracted to the fifth magnetic pole P5 and re-magnetized on the surface of the developing sleeve 51.

When the repulsive magnetic field formed at the inflection point 512 is weak, the developer G is not so far away from the developer G and may be mixed with the developer G pumped up by the pumping unit 511 by the inertial force along the surface moving direction. The developer G that has passed through the development area has a low toner concentration. When development is performed in a state where the developer G is mixed with the developer pumped up normally, the developer G supplied to the development area is used. Thus, an abnormal image in which the image density varies is formed.
On the other hand, in the copying machine 500 provided with the developing device 5 of the present embodiment, the developer G separated at the inflection point 512 can be effectively suppressed from being immediately supplied to the developing sleeve 51, and therefore image fluctuation Can be suppressed, and stable image formation can be performed.

FIG. 6 is an explanatory diagram showing the flow of airflow and developer G in the developing device 5. 6 indicates the flow of the developer G, and the arrow β indicates the flow of the airflow.
The partition plate 520 divides the space where the pumping unit 511 faces and the space where the inflection point 512 faces in the developing device 5, functions as a shielding wall, and together with the developer G separated from the developing sleeve 51, the supply / recovery conveyance path 53 a. A flow path for the air flow toward is formed. Further, since the opening of the pressure release hole 92 inside the casing 60 is located near the lower end of the partition plate 520, the airflow that reaches the vicinity of the lower end of the partition plate 520 along the partition plate 520 has a low atmospheric pressure. It flows into the pressure relief hole 92 communicating with the outside of the casing. Since the pressure relief filter 90 is provided at the opening outside the casing of the pressure relief hole 92, the partition plate 520 is a member that forms a part of the flow path where the airflow goes to the pressure relief filter 90. Yes.

  In the developing device described in Patent Document 1, a through hole provided with a filter member is disposed on the left side of the developing sleeve at a position slightly above the rotation center of the developing sleeve. At this position, as the developer flows downward, the airflow also flows downward. In such a configuration, even if the air pressure increases due to the airflow flowing into the casing together with the developing sleeve, the airflow is discharged out of the developing device through the filter member before the air pressure in the developer accommodating portion of the developing device increases. Further, it is possible to suppress an increase in the atmospheric pressure in the developer accommodating portion.

  However, most of the airflow that has flowed into the casing together with the developing sleeve falls together with the developer into the developer accommodating portion. For this reason, the toner scattered when the developer is separated from the developing sleeve and the toner scattered when the developer separated from the developing sleeve merges with the developer in the developer accommodating portion are developed on the left side of the developing sleeve. It is difficult to reach a position slightly above the rotation center of the sleeve. This means that in order for the toner to reach this position, an airflow is generated that flows backward with respect to the flow of the developer carried by the developing sleeve and falling from the separated position into the developer accommodating portion and the airflow that flows with the developer. It is necessary to make it. For this reason, it can be said that the developing device described in Patent Document 1 has a configuration in which the toner scattered at the position of the filter member hardly reaches.

The developer separated from the developing sleeve falls into the developer supply / conveying path which is a developer accommodating portion. At that time, the toner is in a state of being easily scattered, and the toner is scattered in each direction and moves on an airflow flowing in a direction where the atmospheric pressure is low. If there is a part with poor sealing performance other than the through hole provided with the filter member, the scattered toner collects in this part and flows out of the developing device. When the toner flows out, the inside of the image forming apparatus provided with the developing device is contaminated, which causes a reduction in the quality of the output image and a failure of the member.
In contrast, the developing device 5 of the present embodiment can more effectively suppress the scattered toner from flowing out of the developing device. This is due to the following reason.

  That is, the developer G separated at the inflection point 512 that is the separation position is collected in the supply / recovery conveyance path 53a through the space on the side facing the inflection point 512 with the partition plate 520 interposed therebetween. It flows into the supply / recovery conveyance path 53a. At this time, in the supply / recovery conveyance path 53a, the air pressure rises while the toner is scattered. However, since the opening of the pressure release hole 92 inside the casing 60 is located in the vicinity of the lower end of the partition plate 520 located above the supply / recovery conveyance path 53a, the pressure release hole is directed toward the outside of the casing 60 where the atmospheric pressure is low. Airflow passing through 92 is generated. Since the scattered toner flows in a direction where the atmospheric pressure is low together with the air flow, the scattered toner flows into the pressure release hole 92, but is prevented from flowing out of the casing 60 by the pressure release filter 90 provided in the pressure release hole 92. Is done.

  By disposing the opening of the pressure release hole 92 in the vicinity of the lower end portion of the partition plate 520, the air pressure rises without generating an airflow that flows back to the airflow flowing into the supply / recovery conveyance path 53a together with the developer G. It is possible to cause the gas in the supply / recovery conveyance path 53a to flow out. Thereby, the raise of the atmospheric | air pressure in the supply collection | recovery conveyance path 53a can be suppressed. By suppressing the increase in the atmospheric pressure in the supply / recovery conveyance path 53a, it is possible to suppress the generation of an air flow toward the outside from there even if there is a portion with poor sealing performance in the vicinity of the supply / recovery conveyance path 53a. Accordingly, it is possible to suppress the toner from flowing out of the casing 60 of the developing device 5 together with the airflow from the gap where the pressure release filter 90 is not provided. Therefore, in this embodiment, it is possible to more effectively suppress the toner in the two-component developer from flowing out of the casing 60 by the supply and recovery integrated method. By suppressing the outflow of toner from the developing device 5, the occurrence of contamination in the apparatus of the copying machine 500, which is an image forming apparatus, is suppressed, and deterioration in image quality and member failure due to contamination in the apparatus are suppressed. be able to.

  In the developing device 5, the developer G flows along the inclined surface 521 by the partition plate 520, and even if the toner scatters during the flow, the path through which the scattered toner flows is a path toward the supply / recovery conveyance path 53 a. Alternatively, there is only a passage toward the pressure release hole 92. The partition plate 520 divides the space where the pumping unit 511 is opposed to the space where the inflection point 512 is opposed in the developing device 5 and functions as a shielding wall. Therefore, toner scattering occurs during the flow, and the scattered toner Does not flow to the developing sleeve 51 side. Further, in the pressure release hole 92 communicating with the outside of the developing device 5 through the pressure release filter 90, a negative pressure acts on the development device 5, so that the scattered toner flows in the direction of the pressure release filter 90. It will be.

FIG. 7 is a top view of the developing device 5 in which the development upper case 60a of the casing 60 is not shown. Although the pressure release filter 90 and the partition plate 520 are fixed to the upper casing, only the illustration of the upper casing is omitted in FIG. 7, and the pressure release filter 90 and the partition plate 520 are illustrated.
“W51” in FIG. 7 is the image width, and this image width W51 is the width of the latent image on the surface of the photoconductor 1 in the rotation axis direction of the developing sleeve 51. In FIG. The width of the area of the developing sleeve 51 facing the latent image is shown. Further, “W520” in FIG. 7 is the partition plate width, and the partition plate width W520 is the width of the partition plate 520 in the rotation axis direction of the developing sleeve 51. Furthermore, “W90” in FIG. 7 is the filter width, and the filter width W90 is the width of the pressure relief filter 90 in the rotation axis direction of the developing sleeve 51.

As shown in FIG. 7, the image width W51 is within the range of the partition plate width W520, and the partition plate width W520 is within the range of the filter width W90. As shown in FIG. 7, the partition plate 520 is provided over the entire area of the image width W <b> 51 in the developing sleeve 51, so that the toners scattered from the developer G separated from the developing sleeve 51 are discharged to the pressure release hole 92. I can guide you. As a result, it is possible to guide to the pressure relief filter 90 arranged at the upper part of the developing device 5.
Further, the width of the pressure release hole 92 in the rotation axis direction of the developing sleeve 51 is wider than the image width W 51, and the image width W 51 is within the range of the width of the pressure release hole 92. Since the width of the pressure release hole 92 on the downstream side of the flow path of the air flow toward the pressure release filter 90 is wider than the image width W51, the air flow toward the pressure release filter 90 is easily generated.

In addition, the supply / recovery screw 53 of the developer supply / conveyance member rotates the screw blade portion 53c which is a conveyance blade portion around a screw shaft 53b which is a conveyance rotation shaft extending in the rotation axis direction of the developing sleeve 51. Thus, the developer G in the supply / recovery conveyance path 53a is conveyed.
Here, in the space that is divided into two in the horizontal direction with the screw shaft 53b as a boundary in the supply / recovery conveyance path 53a, the space in which the screw blade portion 53c moves upward from below as the supply / recovery screw 53 rotates (see FIG. The space on the right side in 1) is defined as the wing rising space. On the other hand, a space (left space in FIG. 1) in which the screw blade portion 53c moves downward from above with the rotation of the supply / recovery screw 53 is defined as a blade-lowering space. At this time, as shown in FIG. 1, the developer G in the supply / recovery conveyance path 53a is supplied to the surface of the developing sleeve 51 from the wing rising space, and the lower end portion of the partition plate 520 is located above the screw shaft 53b or Located above the wing down space.

  With such a configuration, the developer G separated from the developing sleeve 51 at the inflection point 512 is transferred into the wing descending space, and is supplied, recovered, and conveyed along with the movement of the screw wing 53c in the wing descending space. It is taken into the developer G in the passage 53a and stirred. Accordingly, it is possible to more effectively suppress the developer G separated from the developing sleeve 51 from being immediately supplied to the developing sleeve 51 without being stirred with the developer G in the supply / recovery conveyance path 53a.

  As shown in FIG. 1, the partition plate 520 is inclined so that the horizontal position with respect to the rotation axis of the developing sleeve 51 is separated from the upper end portion to the lower end portion. With such a configuration, all of the developer G separated from the developing sleeve 51 at the inflection point 512 can be dropped to the far side from the developing sleeve 51 with the screw shaft 53b interposed between the partition plates 520. Thereby, it is possible to further effectively suppress the developer G separated at the inflection point 512 from being immediately supplied to the developing sleeve 51.

FIG. 8 is an enlarged cross-sectional view of the vicinity of the partition plate 520 of the developing device 5.
FIG. 8 shows the state of the developer G that is separated from the surface of the developing sleeve 51 and falls into the supply / recovery conveyance path 53a, and the solid line arrows shown together with the developer G in the figure indicate the path of the developer G. The broken line arrows in the figure indicate the path of the airflow.

  The developer G separated from the developing sleeve 51 (the surface of the developing roller 50) at the inflection point 512 is along the inclined surface 521 of the partition plate 520 with respect to the horizontal direction across the screw shaft 53b of the supply and recovery screw 53. Falls to the far side. At the inflection point 512, the developer G is the part farthest away from the developing sleeve 51. Therefore, as shown in FIG. 8, the developer G separated from the developing sleeve 51 falls straight along the direction of gravity, and the partition plate The inclined surface 521 of 520 is landed.

  The inclined surface 521 of the partition plate 520 is inclined with respect to the direction of gravity, and the developer G moves along the inclined surface 521. As a result, in the horizontal direction, the supply / recovery transport is on the side farther from the developing sleeve 51 than just below the inflection point 512 and farther from the developing sleeve 51 than the perpendicular drawn from the center of the screw shaft 53b of the supply / recovery screw 53 The developer G is dropped into the path 53a.

As shown in FIG. 8, the developing device 5 includes a rectifying member 91 at the lower end portion of the sleeve facing surface 601 that faces the developing sleeve 51 among the inner wall surface of the casing 60. The rectifying member 91 is a member that changes the flow direction so that the path of the airflow flowing along the sleeve facing surface 601 is directed to the inclined surface 521 of the partition plate 520.
When the developer G falls into the supply / recovery conveyance path 53a, the airflow deflected toward the partition plate 520 by the rectifying member 91 tends to scatter when the developer G leaves the inflection point 512. To the direction of the partition plate 520. Since the airflow is blown toward the developer G on the partition plate 520, the developer G accumulates on the partition plate 520 and is clogged (packed) between the partition plate 520 and the rectifying member 91. Can be prevented.

The lower end portion of the rectifying member 91 extends in the axial direction so as to face substantially the center of the inclined surface 521 of the partition plate 520 when viewed in the cross section shown in FIG. 8, and the partition plate 520 at this position. And the flow regulating member 91 become the narrowest (indicated by an arrow “W91” in the figure). Therefore, the flow velocity of the airflow is the fastest at this position, and the force sprayed on the partition plate 520 is increased. Further, the gap between the partition plate 520 and the rectifying member 91 (the width indicated by the arrow “W91” in the figure) is actually reduced by the amount of the developer G riding on the inclined surface 521 of the partition plate 520. Therefore it becomes narrow. The airflow that has passed through the position where the flow path becomes narrower escapes toward the pressure relief hole 92, which is the path where the pressure relief filter 90 having a relatively low pressure is disposed. Depressurizing the filter 90 is a path which is arranged the inlet of the gap (the width shown by arrow "W9 2") of the pressure release hole 92, the partition plate 520 shown by arrow "W91" and rectifying member 91 It is set to be larger than the width of the gap, making it easy to draw in the airflow.

  In addition, a small amount of toner may fly up and scatter when the developer falls on a supply / recovery conveyance path 53a which is a development side accommodation chamber in which a supply / recovery screw 53 which is a conveyance screw on the developing roller 50 side is accommodated. is there. The scattered toner acts like a curtain on the falling developer G, and it is difficult for the scattered toner to move to the developing sleeve 51 side from the lower end of the partition plate 520. Since the upper part of the dropping position is open, the scattered toner moves toward this space. In this space, as described above, since there is an air flow toward the depressurization hole 92 in which the depressurization filter 90 is disposed, the airflow due to the drop of the developer G and the scattered toner are easily drawn by the negative pressure.

  As shown in FIG. 1, the lower end portion of the partition plate 520 is positioned above the upper end portion of the supply / recovery screw 53, and does not contact the developer G in the supply / recovery conveyance path 53a. A flexible sheet member such as Mylar may be provided at the lower end portion of the partition plate 520, and the lower end portion may be in contact with the developer G in the supply / recovery conveyance path 53a. By providing such a sheet member, it is possible to reliably supply the developer G separated from the developing sleeve 51 into the developer G in the supply / recovery conveyance path 53a that descends in the wing portion descending space. Thereby, it is possible to more effectively suppress the developer G separated at the inflection point 512 from being immediately supplied to the developing sleeve 51.

FIG. 9 is a cross-sectional explanatory view of the developing device 5 before starting use, and FIG. 10 is a perspective explanatory view of the developing device 5 before use. The image forming unit 6 shown in FIG. 4 is also in a state before use.
The casing 60 of the developing device 5 includes a developing upper case 60a including the inner wall of the developing roller accommodating portion 62, and a developing lower case 60b including the inner wall of the developer accommodating portion constituted by the supply / recovery conveying path 53a and the circulation conveying path 54a. And it is mainly composed. A developing sleeve 51 is attached to the lower developing case 60b via a bearing (not shown), and a doctor blade 52, a magnetic plate 58, and the like are also attached. The upper development case 60a is attached to the upper side of the lower development case 60b to which these members are attached.

Further, the lower developing case 60b has a communication port seal that seals a communication port 59 that connects the developing roller accommodating portion 62 formed by the upper developing case 60a and the supply / recovery conveyance path 53a formed by the lower developing case 60b. A stop member 80 is attached. The communication port sealing member 80 is a member that prevents the developer from leaking and scattering from the opening 61 of the developing roller housing 62 when the image forming unit 6 is carried alone. Further, since the communication port sealing member 80 seals the communication port 59, the developer accommodating portion is blocked from the outside air, so that the developer G can be prevented from being deteriorated due to the developer G coming into contact with air. it can. At the start of use, the sealing by the communication port sealing member 80 is released, and the above-described image forming operation is performed.

  FIG. 11 is an exploded perspective view of a communication port sealing member 80 which is a communication port sealing means. The communication port sealing member 80 includes a frame body 81 that forms an opening as the communication port 59 and a seal member 82 that is directly bonded to the frame body 81 by thermocompression bonding (heat sealing) so as to cover the opening. ing. The seal member 82 is bonded to the frame body 81 from the front side end portion to the back side end portion in FIG. 9 so as to cover the opening serving as the communication port 59, and seals the communication port 59. The tip portion is returned to the front end portion by being folded back at the portion. In order to pull out the seal member 82, the tip end portion protrudes outward from the end portion of the frame 81 as shown in FIG. 4 and FIG.

  By pulling out the margin of the seal member 82 in the right front direction in FIG. 11 in parallel with the opening surface, the seal member 82 thermally bonded to the frame body 81 is peeled off, and the opening formed in the frame body 81 appears, and the supply and recovery are performed. A communication port 59 between the conveyance path 53a and the developing roller accommodating portion 62 is formed. As a result, the developer can be supplied from the supply / recovery conveyance path 53 a to the developing roller accommodating portion 62 through the communication port 59.

  In addition, the frame body 81 has a bent portion 83 formed by bending the end portion of the frame body located in the lateral direction with respect to the direction in which the seal member 82 is pulled out. By providing such a bent portion 83, it is possible to secure strength against a force that pulls the seal member 82 in a direction parallel to the opening surface and peels it from the frame 81.

  As a material of the frame body 81, a resin material which is polypropylene (PP) and is strong against bending is used. The reason why the material is polypropylene (PP) is that the moldability is better than that of PET resin, and even a thick plate can be stably formed without causing cracks, fluffing and the like. It is. When a crack is generated, foreign matter such as dust at the cracked portion may enter the developer and an abnormal image such as a white stripe may be generated. In addition, the plate thickness is 0.8 [mm] or less. By providing the bent portion 83 in the frame body 81, it is possible to provide sufficient strength even with such a plate thickness as compared with a flat plate. Moreover, since polypropylene (PP) is used, it is cheaper than PET resin.

  As the seal member 82, an easy peel film (manufactured by Sanei Kaken) was used. The sealing member 82 made of this easy peel film is directly bonded to the polypropylene frame 81 by thermocompression bonding without using a double-sided tape. For this reason, when the seal member 82 is peeled off, there is no possibility that the double-sided tape abuts on the developing sleeve 51 or is mixed into the developing roller accommodating portion 62 to generate an abnormal image. Further, compared to the two-step manufacturing process in which the sealing member 82 is further bonded after the double-sided tape is applied, the manufacturing process is easy because the sealing member is directly bonded by thermocompression bonding.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
The developer carrying member such as the developing sleeve 51 that rotates so as to move the surface from below to above in the developing region, and the developer so that the surface of the developer carrying member faces the surface of the latent image carrier such as the photosensitive member 1. A developing opening such as an opening 61 for exposing a part of the surface of the developer carrying member in the moving direction of the carrying member is provided, and a two-component developer such as developer G containing toner and a magnetic carrier is accommodated therein. A developer supply conveyance path such as a supply collection conveyance path 53a that extends in the direction of the rotation axis of the developer carrier below the developer carrier in the casing Development of a supply / recovery screw 53 or the like that supplies the two-component developer in the developer supply / conveyance path to the surface of the developer carrier while conveying the two-component developer in the developer along the axial direction of the developer carrier. Agent supply and conveyance member The two-component developer carried on the surface of the developer carrier is transported to the development area, and the toner in the two-component developer is attached to the latent image on the surface of the latent image carrier in the development area to develop the latent image. In addition, in the developing device such as the developing device 5 that separates the two-component developer that has passed through the developing region from the developer carrying member and collects the developer in the developer carrying path, the developer is supplied on the surface of the developer carrying member. Between the supply position of the pumping unit 511 or the like to which the two-component developer is supplied from the conveyance path and the separation position such as the inflection point 512 or the like where the two-component developer that has passed through the development region is separated from the developer carrier. The upper end of the developer carrying member is opposed to the entire surface in the direction of the rotation axis of the developer carrier, the space where the supply position in the developing device is opposed to the space where the separation position is opposed, and the lower end is the developer. Partition plate 52 located above the supply conveyance path The casing is provided with a through hole such as a pressure relief hole 92 provided with a filter member such as a pressure relief filter 90 that allows gas to pass while preventing the toner and magnetic carrier from passing therethrough. The opening of the hole inside the casing is located near the lower end of the partition plate.
According to this, as described in the above embodiment, the developer separated at the separation position passes through the space on the side where the separation position opposes across the partition plate, and is collected in the developer supply conveyance path. At the same time, an airflow also flows into the developer supply conveyance path. At this time, in the developer supply conveyance path, the air pressure rises while the toner is scattered, but an opening on the inside of the casing of the through hole is formed near the lower end of the partition plate located above the developer supply conveyance path. Therefore, an air flow passing through the through hole is generated toward the outside of the casing where the atmospheric pressure is low. Since the scattered toner flows in a direction where the air pressure is low together with the air flow, the scattered toner flows into the through hole, but the filter member provided in the through hole prevents the outflow from the casing. By arranging the opening of the through hole in the vicinity of the lower end portion of the partition plate, development that tends to increase the air pressure without generating an airflow that flows backward with respect to the airflow flowing into the developer supply transport path together with the developer. The gas in the agent supply / conveyance path can be discharged to the outside, and an increase in atmospheric pressure can be suppressed. By suppressing the increase in the air pressure in the developer supply transport path, even if there is a portion with poor sealing properties in the vicinity of the developer supply transport path, it is possible to suppress the generation of an air flow from there to the outside. Accordingly, it is possible to suppress the toner from flowing out of the casing of the developing device together with the airflow from the gap not provided with the filter member. Therefore, in this aspect, it is possible to more effectively suppress the toner in the two-component developer from flowing out of the casing by the supply and recovery integrated system.
(Aspect B)
In the aspect A, the developer supply / conveyance member such as the supply / recovery screw 53 is a screw blade portion 53c centering on a conveyance rotation axis such as a screw shaft 53b extending in the rotation axis direction of the developer carrier such as the development sleeve 51. The two-component developer such as developer G in the developer supply transport path such as the supply / recovery transport path 53a is transported by the rotation of the transport blades of the developer, and the developer supply transport member The space divided into two in the horizontal direction with the conveyance rotation axis as the boundary, the wing rising space where the conveyance wing moves from below to above with the rotation of the developer supply conveyance member, and the conveyance wing from below The developer in the developer supply transport path is supplied from the wing lift space to the surface of the developer carrying member, and the lower end of the partition plate such as the partition plate 520 is transported and rotated. Above the shaft or above the wing down space Located in.
According to this, as described in the above embodiment, the developer separated from the developer carrier at the separation position is transferred into the wing descending space, and the transport wing moves in the wing descending space. Accordingly, the toner is taken into the developer in the developer supply conveyance path and stirred. Thereby, it can suppress more effectively that the developer separated from the developer carrier is immediately supplied to the developer carrier without being agitated with the developer in the developer supply conveyance path.
(Aspect C)
In any of the aspects A and B, the partition plate such as the partition plate 520 is inclined so that the horizontal position with respect to the rotation axis of the developer carrier is separated from the upper end portion to the lower end portion.
According to this, as described in the above embodiment, all of the developer separated from the developer carrying member at the separated position can be dropped to the far side from the developer carrying member with the conveyance rotation shaft interposed between the partition plates. . Thereby, it can suppress more effectively that the developer separated in the separation position is immediately supplied to the developer carrying member.
(Aspect D)
In any of the aspects A to C, the width of the through hole such as the pressure release hole 92 in the rotation axis direction of the developer carrier such as the developing sleeve 51 is set on the surface of the latent image carrier such as the photoreceptor 1. It is wider than the width of the latent image (image width W51 etc.).
According to this, as described in the above embodiment, the width of the through hole on the downstream side of the flow path of the air flow toward the filter member such as the depressurizing filter 90 is wider than the width of the latent image. It becomes easy to generate the air flow toward. For this reason, it is difficult to generate an airflow in the other direction, and it is possible to prevent the toner from being scattered outside through a gap between the casings not including the filter member.
(Aspect E)
In any one of the aspects A to D, among the inner wall surfaces of the casing such as the casing 60, along the developer bearing member facing surface such as the sleeve facing surface 601 facing the surface of the developer bearing member such as the developing sleeve 51. A rectifying member such as a rectifying member 91 that changes the direction of the flow so that the flowing airflow is directed to a partition plate such as the partition plate 520 is provided.
According to this, as described in the above embodiment, the two-component developer such as the developer G from the separation position such as the inflection point 512 is generated by the air flow whose direction of flow is changed toward the partition plate by the rectifying member. When leaving, the toner to be scattered is suppressed toward the partition plate. As a result, the toner is prevented from flying up from the two-component developer before reaching the lower end of the partition plate 520 after being separated from the developer carrying member, and the toner is scattered outside from the gap of the casing not provided with the filter member. Can be prevented.
(Aspect F)
At least a latent image carrier and a developing unit in an image forming apparatus such as a copying machine 500 including a latent image carrier such as the photosensitive member 1 that carries the latent image and a developing unit that develops the latent image on the latent image carrier. In the process cartridge such as the image forming unit 6 that is held on a common holder as a unit and can be attached to and detached from the image forming apparatus main body, the developing device according to any one of the aspects A to E is used as the developing unit. A developing device such as 5 is used.
According to this, as described in the above embodiment, the development in the image forming apparatus including the developing device that can more effectively suppress the toner in the two-component developer from flowing out of the casing. The apparatus can be easily replaced, and the maintainability of the image forming apparatus is improved.
(Aspect G)
At least a latent image carrier such as the photosensitive member 1, a charging unit such as a charging device 40 for charging the surface of the latent image carrier, an exposure device 12 for forming an electrostatic latent image on the latent image carrier, and the like. In the image forming apparatus such as the copying machine 500 having the latent image forming unit and the developing unit for developing the electrostatic latent image into a toner image, the developing unit is any one of the modes A to E. A developing device such as the developing device 5 is used.
According to this, as described in the above embodiment, it is possible to suppress in-apparatus contamination caused by the toner in the two-component developer flowing out of the casing, and an image resulting from in-apparatus contamination. It is possible to suppress deterioration in quality and member failure.

DESCRIPTION OF SYMBOLS 1 Photoconductor 1Y Yellow photoconductor 1C Cyan photoconductor 1K Black photoconductor 1M Magenta photoconductor 2 Photoconductor cleaning device 2a Cleaning blade 3 Document transport unit 4 Document reading unit 4a Charging roller 5 Developing device 6 Image forming unit 6Y Yellow image forming unit 7 Paper feed unit 8 Intermediate transfer belt 9 Primary transfer bias roller 10 Intermediate transfer unit 11 Toner container 12 Exposure device 19 Secondary transfer bias roller 20 Fixing device 25 Paper discharge roller pair 26 Paper feed cassette 27 Paper feed roller 28 registration roller pair 30 discharge tray 40 charging device 50 developing roller 51 developing sleeve 52 doctor blade 53 supply recovery screw 53a supply recovery conveyance path 53c screw blade part 53b screw shaft 54 circulation screw 54a circulation conveyance path 55 magnet roller 56 density detection sensor 5 Partition wall 57a Circulation downstream end opening 57b Supply downstream end opening 58 Magnetic plate 58a Opposing surface 59 Communication port 60 Casing 60a Development upper case 60b Development lower case 61 Opening portion 62 Development roller storage portion 64 Toner replenishment port 80 Communication port sealing Member 81 Frame 82 Seal member 83 Bending part 90 Depressurizing filter 91 Rectifying member 92 Depressurizing hole 100 Printer part 500 Copying machine 511 Pumping part 512 Inflection point 520 Partition plate 521 Inclined surface 601 Sleeve facing surface G Developer L Laser light P Transfer paper P1 First magnetic pole P2 Second magnetic pole P3 Third magnetic pole P4 Fourth magnetic pole P5 Fifth magnetic pole W51 Image width W520 Partition width W90 Filter width

JP 2010-237635 A JP 2007-047637 A Patent No. 5240553

Claims (7)

A developer carrier that rotates to move from the bottom to the top in the development region;
A developer opening is provided for exposing a part of the surface of the developer carrier in the direction of movement of the developer carrier so that the surface of the developer carrier faces the surface of the latent image carrier. A casing containing a two-component developer containing a carrier;
A two-component developer in the developer supply transport path is disposed in the developer supply transport path extending in the direction of the rotation axis of the developer support below the developer support in the casing. A developer supply transport member that supplies the two-component developer in the developer supply transport path to the surface of the developer carrier while transporting along the axial direction of the body,
The two-component developer carried on the surface of the developer carrying member is transported to a developing region, and the toner in the two-component developer is attached to the latent image on the surface of the latent image carrying member in the developing region. And developing the two-component developer that has passed through the development area away from the developer carrier and collecting it in the developer supply conveyance path.
On the surface of the developer carrier, a supply position where the two-component developer is supplied from within the developer supply transport path, and a separation position where the two-component developer that has passed through the development area is separated from the developer carrier. Between the space where the upper end portion faces the entire surface in the rotation axis direction of the developer carrier and the supply position in the developing device faces and the space where the separation position faces. With a partition plate located between
A lower end portion of the partition plate is located above the developer supply transport member;
The opening inside the casing of the through hole provided with a filter member that allows gas to pass while preventing the toner and magnetic carrier from passing is located near the lower end of the partition plate,
When viewed from the axial direction, the casing inner side of the opening width of the through hole is in space where the separating position is opposed, the two-component developer between the opposing member and the partition plate to the partition plate A developing device characterized in that it is wider than the moving gap. The developing device according to claim 1.
The developer supply / conveyance member conveys the two-component developer in the developer supply / conveyance path by rotating a conveyance blade centering on a conveyance rotation axis extending in a rotation axis direction of the developer carrier. ,
In the developer supply / conveyance path, a space divided into two in the horizontal direction with the conveyance rotation axis of the developer supply / conveyance member as a boundary, and the conveyance blades from the lower side as the developer supply / conveyance member rotates. When the wing rising space that moves upward and the wing lowering space in which the transport wing moves downward from above,
The developer in the developer supply conveyance path is supplied to the developer carrier surface from the wing rising space,
The developing device according to claim 1, wherein a lower end portion of the partition plate is located above the conveyance rotation shaft or above the wing portion descending space. In the developing device according to claim 1 or 2,
The developing device, wherein the partition plate is inclined so that a horizontal position with respect to a rotation axis of the developer carrying member is separated from an upper end portion to a lower end portion. The developing device according to any one of claims 1 to 3,
The developing device according to claim 1, wherein the width of the through hole in the rotation axis direction of the developer carrying member is wider than the width of the latent image on the surface of the latent image carrying member. In the developing device according to any one of claims 1 to 4,
A rectifying member that changes a flow direction so that an airflow flowing along a developer carrier facing surface that faces a surface of the developer carrier among the inner wall surfaces of the casing is directed to the partition plate; A developing device. A latent image carrier for carrying a latent image;
In an image forming apparatus including a developing unit that develops a latent image on the latent image carrier, at least the latent image carrier and the developing unit are held as a single unit on a common holder, and the main body of the image forming apparatus. In the process cartridge that can be attached and detached,
A process cartridge using the developing device according to claim 1 as the developing means. At least a latent image carrier;
Charging means for charging the surface of the latent image carrier;
A latent image forming means for forming an electrostatic latent image on the latent image carrier;
In an image forming apparatus having developing means for developing the electrostatic latent image into a toner image,
An image forming apparatus using the developing device according to claim 1 as the developing unit.

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